Protein composition obtained from meat trimmings

ABSTRACT

A protein fraction and an oxidation stable fat fraction are recovered from meat trimmings. The trimmings are comminuted, mixed with a food grade acid at pH 3.6 to 4.4 to form a liquid protein fraction and a solid fat fraction. The liquid fraction is mixed with a food grade alkali to precipitate the protein. A myoglobin rich fraction is recovered from the protein fraction and mixed with the precipitated protein.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/872,279, entitled, “Protein Composition Obtained From Meat Trimmings”by Stephen D Kelleher, et al., filed Oct. 1, 2015, which is acontinuation of U.S. patent application Ser. No. 13/374,077, now U.S.Pat. No. 9,161,555, entitled “Process for isolating a proteincomposition and a fat composition from meat trimmings,” by Stephen DKelleher, et al., filed Dec. 12, 2011 which is a non-provisional ofProvisional Application No. 61/460,324, entitled “Process for isolatinga protein composition and a fat composition from meat trimmings,” byStephen D Kelleher, et al., filed Jan. 3, 2011.

The entire teachings of the above application(s) are incorporated hereinby reference.

FIELD OF THE INVENTION

This invention relates to a process for isolating a protein compositionand a stable fat composition from a fatty composition comprising meattrimmings containing animal muscle tissue. More particularly, thisinvention relates to such a process wherein the animal muscle tissue issolubilized in an acid and the liquid acidic protein composition soobtained is separated from solid animal fat under conditions (a) toinactivate microorganisms, (b) to reduce sodium concentrations, (c) tostabilize the fat against oxidation and (d) to obtain solubilized animalmuscle tissue having a satisfactory color.

DESCRIPTION OF PRIOR ART

At the present time, protein recovered from animal muscle tissue isobtained by solubilizing the animal muscle tissue in an edible acidiccomposition such as citric acid, hydrochloric acid or mixtures thereof.Such processes are disclosed in U.S. Pat. Nos. 6,005,073; 6,288,216;6,451,975 and 7,473,364. While these processes are well adapted forrecovering protein from animal muscle tissue, they are not well adaptedfor recovering, with high efficiency, protein and fat from meattrimmings. These meat trimmings contain a high concentration of animalmuscle tissue, typically between 30-50% by weight of the trimmings withthe remaining composition comprising primarily fat. Thus, it isdesirable to recover the protein from the animal muscle tissue for useas a food additive rather than discarding it. It is also desirable torecover purified and stabilized fat from the trimmings which haseconomic value such as for a food additive or for producing tallow.

Presently, animal muscle protein is recovered from meat trimmings by aprocess which includes a step of dissolving the animal fat tissue usingthermal energy, while further processing with the use of an alkalineagent e.g., ammonia, ammonium hydroxide, to control bacteria such as isdisclosed in U.S. Pat. No. 5,871,795. This process may be undesirablesince the recovered protein product can potentially have a smell ofammonia if the resting pH is too high. Thus, it can be used onlysparingly as a food additive.

Another method for separating animal muscle tissue from fat is disclosedin U.S. Pat. No. 7,666,456. In this method, comminuted trimmings aremixed with warm water containing carbon dioxide. This water basedcomposition has a density which is intermediate of the density of thefat and the density of the animal muscle tissue. The fat particles areseparated from the animal muscle tissue particles on the basis ofdiffering density wherein the fat particles float on the water basedcomposition and the animal muscle tissue particles sink to the bottom ofthe water based composition. During the process both the fat particlesand the animal muscle tissue particles remain in the solid state. It isalso disclosed that the pH of the water based composition can drop toless than 2 and that this can reduce the bacterial population that ispresent at the animal muscle tissue surfaces.

A further problem with recovering animal muscle protein from fattyanimal tissue is that the protein can contain microorganisms such as E.coli that are unsuitable for human consumption. One method fordestroying microorganisms involves the use of ammonium hydroxide, whichhas the problem set forth above and, thus, is undesirable. Additionalproblems regarding samples treated with alkaline agents e.g., ammonia orammonia hydroxide, are that these treated samples have reduced essentialamino acid percentages and lower functionality or water binding ability.

The process disclosed in U.S. Pat. No. 6,949,265 discloses a method forreducing or eliminating surface bacteria and pathogens by pre-scaldingtrimmings. The muscle tissue is separated from fat tissue by heat toliquefy the fat tissue but below 110° F. so as to avoid cooking themuscle tissue while the muscle tissue remains solid. The liquid fat isthen separated from the solid muscle tissue. This process may beundesirable since microorganisms grow rapidly at elevated temperaturesbetween about 40° F. and about 140° F.

It is also desirable to process animal muscle tissue in a manner whichretains functionality of the recovered protein product. Proteinfunctionalities of most concern to food scientists are solubility, waterholding capacity, gelation, foam stability and emulsificationproperties.

It is also desirable to process the animal tissue in a manner whichresults in a final product that has large fibers, which better resemblesfine ground or coarse ground beef.

It is also desirable to provide a process for producing a fat fractionhaving a relatively low concentration of water and which is stableagainst oxidation. Such a form of fat permits its addition to a varietyof food products such as beef products.

The U.S. government provides that a certain quality of meat productobtained from animal trimmings can be used undeclared in meat productsof the same species. For example, “finely textured beef” and “leanfinely textured beef” can be used in ground beef without being declaredon the label. “Finely textured meat” is required to have a fat contentof less than 30%; a protein content of 14% or greater, by weight; aprotein efficiency ratio (PER) of 2.5 or higher, or an essential aminoacids (EAA) content of 33% of the total amino acids or higher; must beprepared in a federally inspected plant; must not have a producttemperature during processing exceeding 110° F.; must be frozen in lessthan 30 minutes after processing; must not allow a significant increasein bacterial numbers; and must not be treated with chemicals oradditives that remain in the meat. “Lean finely textured meat” (LFTM) isrequired to have a fat content of less than 10%, by weight, and complieswith the other requirements of “finely textured meat”.

Accordingly, it would be desirable to provide a process for isolatinganimal muscle protein from fatty animal tissue containing animal muscletissue such as trimmings which provides high yields of functional animalmuscle protein while significantly destroying microorganisms.Furthermore, it would be desirable to provide a fat product fromtrimmings which is stable against oxidation and which has a relativelylow concentration of water. Also, it would be desirable to provide ananimal muscle protein product that has a similar or reduced sodiumcontent as compared to the original meat. In addition, it would bedesirable to provide such a process which eliminates undesirable smellcharacteristics such as the smell of ammonia. Furthermore it woulddesirable to produce a final beef product that has large fibers whichresults in a more desirable ground beef-like texture and mouth feel.Such a process would provide high recovery rates of fat stable againstoxidation and of animal muscle protein in a low microorganismenvironment while avoiding the addition and retention of ingredientswhich adversely affect edibility of the protein product. In addition, itwould be desirable to provide such an animal muscle tissue proteinhaving a color which permits its satisfactory addition to high proteinfoods such as ground beef.

SUMMARY OF THE INVENTION

In accordance with this invention, a process is provided for isolatingboth animal muscle protein having a satisfactory color and fatstabilized against oxidation from meat trimmings comprising animalmuscle tissue and fat. The process provides high yields of functionalanimal muscle protein having satisfactory color while avoiding problemsdue to the presence of microorganisms and avoiding problems which renderthe recovered proteins inedible. The process of this invention alsoprovides a fat product which is stable against oxidation and whichcontains a relatively low water concentration. The process of thisinvention is capable of meeting the definition of “finely textured meat”or “lean finely textured meat” as presently defined by the U.S.government.

The process of this invention includes the process steps of comminutingfresh or frozen meat trimmings, adding cold potable water to thecomminuted trimmings; optionally adding a food grade acid; homogenizingthe trimmings-water mixture; adding a food grade acid to the homogenizedtrimmings to lower the pH of the resultant mixture to between 3.6 to4.4, preferably between 3.6 and 3.8 to selectively dissolve the animalmuscle tissue; separating the solid fat from the acidic solution ofanimal muscle protein; recovering the solid fat; optionally evaporatingwater from the acidic solution of animal muscle protein to form aconcentrated protein solution; recovering the acidic solution of animalmuscle protein or adding a food grade alkaline composition to the acidicanimal muscle protein solution to increase the pH to between about 4.9and about 6.4, preferably between about 5.2 and about 5.8 to form a saltfrom the reaction of the acid with the alkaline composition and toprecipitate the protein, separating the solid protein from the remainingliquid such as by centrifugation and/or screen filtration and optionallyfreezing the resultant essentially neutral animal muscle proteincomposition.

It has been found that when reducing the pH of animal muscle tissue from3.6 to 4.4 in accordance with this invention, the animal muscle tissueis solubilized while retaining essentially its original color and thatsatisfactory yields of muscle tissue (protein) are obtained. In order torender the solubilized animal muscle tissue useful for addition toground animal muscle tissue such as beef hamburger, the solubilizedanimal muscle tissue should have a color of 75 to 52 L*, 25 to 10 a* and23 to 16 b* wherein L*, a* and b* are defined according to theCommission Interntionale de I'Eclarage (CIE) as L* (luminance or musclelightness), a* (redness or muscle redness), b* (yellowness or muscleyellowness). For example in the case of beef muscle tissue, the originalred color is retained. In contrast, when the pH is about 3.5 or less,the tissue color becomes brown and does not revert to its originalcolor. A protein composition having a brown color is not suitable foraddition to a food having a normal red color such as hamburger. It hasalso been found that solubilization of the animal muscle tissue in acidresults in a significant reduction of viable microorganisms,particularly when utilizing food grade hydrochloric acid as the acid.One particular food grade acid and base combination of interest in thispresent invention is citric acid to lower the pH and sodium bicarbonateto raise the pH. It has also been found that mixing the fat with foodgrade acid in accordance with this invention, stabilizes the fat againstoxidation. In addition, it has been found that when mixing the fatcontaining acid with a food grade base to a pH between about 4.9 andabout 5.8 effects separation of water from the fat from about 70 toabout 50 weight % down to a water content between about 30 and about 20weight percent. This result simplifies subsequent water removal from thefat if such additional water removal is desired. Lastly, in the processof this invention, the presence of undesirable acidic or alkalineadditives in the final protein product is eliminated due to theneutralization of the acid with the alkaline.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a process flow diagram of the process of this invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The present invention relates to a method for processing animaltrimmings to recover meat products low in fat content and high inprotein and essential amino acid content as well as a stabilized fatproduct. “Meat product” describes a protein-containing product which issuitable for human consumption as meat because it contains a certainamount of protein. Generally, “trimmings” refers to the tissue cut awayfrom conventional cuts or parts of the carcasses of meat producinganimals during butchering operations in packing houses and the like. Theconventional cuts or parts are generally sold directly to consumers orfurther processed by, for example, grinding into ground beef. The tissueremaining after the conventional cuts are removed, or after theconventional cuts have been further trimmed, generally has a fat contentwhich is too high for human consumption as meat, but contains proteinswhich can be recovered.

According to the present invention, once the trimmings are removed fromthe carcasses, they are preferably forwarded directly to the process ofthe present invention. Alternatively, the trimmings can be frozen orcooled and stored prior to processing. The temperature of the trimmings,upon removal from the carcasses is usually about 33-40° F. whichcorresponds to the temperature at which the carcasses are stored priorto butchering. Warmer or cooler trimmings can be used in the process ofthe present invention.

The trimmings can include any part of an animal which is trimmed awayfrom the carcass of the animal or the cuts. The trimmings can includeall the parts normally found in an animal, including adipose tissue,fat, lean ligaments, tendons, bone parts, and the like. It is generallydesirable that if components other than fat, lean, and moisture arepresent, they are present in small quantities and/or can be removed inthe desinewing step or by hand, if desired, or can be left therein iftheir presence does not adversely affect the properties of the meatproduct. If large amounts of certain components are present, it may bedesirable to have them removed by conventional separation techniquesprior to processing according to the present invention. For example, itis generally desirable not to have large amounts of bone present orlarge amounts of low quality ligaments.

“Meat producing animals” includes animals which are known to providemeat. Such animals include beef, pork, poultry such as chicken orturkey, e.g. mechanically deboned chicken, lamb, deer, buffalo, fish,and the like. The lean material can be referred to as protein-containingmaterial, and can be in the form of water soluble protein which includemuscle fiber, and non-water soluble protein which are generally themyofibrilar or locomotion proteins or the connective tissue whichsurrounds muscle fiber and which attach the muscle fibers to ligaments.Of particular interest for purposes of the present invention is thepresence of the water soluble protein and the acid soluble protein fromthe animal muscle tissue in the fatty tissue within the fat trimmings.By separating this protein material from the animal trimmings, a highquality meat product can be provided. This product can be utilized as anadditive to conventional meat products such as to hamburger.

Animal trimmings, which can be used in the present invention preferably,have an average fat content of between about 50 and 80% by weight,preferably between about 50 and 70% by weight. The lean content of theanimal trimmings is preferably between about 20 and 50% by weight, andmore preferably between about 30 and 50% by weight. The lean contentincludes protein and moisture. In order to ensure reliable andconsistent results, it is preferable that the lean content of the animaltrimmings is at least about 30% by weight and preferable at least about39% by weight.

Referring to FIG. 1 which illustrates a preferred embodiment of thisinvention, boneless trimmings 12 such as beef trimmings containing about50% by weight beef muscle tissue and about 50% by weight fat,mechanically separated chicken or the like are directed to a comminutionstep 14 which increases the surface area of the beef trimmings renderingit more suitable for further processing. Advanced Recovered Meat (AMR)also can be utilized as a feed. Suitable comminution apparatus includemeat grinder available from Weiler and Company Corporation located inWhitewater, Wis. or Carnitec USA, Inc, located in Seattle, Wash. Thestarting meat trimmings are first ground to a size that enables it to beput through a micro-cutter. It is preferable to coarse cut ¾ inch,followed by a ⅛ inch grind. Once ground, the material is mixed withwater (33-40° F.) at a ratio of one part ground meat to approximately5-6 parts water. This amount of water can vary and can go as high asapproximately 1 part ground meat to 10 parts cold water. The addition ofwater lowers the ionic strength of the homogenate which is required forcomplete solubilization of the proteins. Optionally, acid can be addedto the trimmings in step 20 to improve protein solubilization. Thecomminuted trimmings are directed to homogenization step 16 where it ismixed with potable water 18 at a water temperature typically betweenabout 33° F. and about 40° F. and homogenized, typically to an averageparticle size of about 0.5 to about 4 millimeters preferably betweenabout 1 to about 2 millimeters. A preference has been shown for amicro-cut with a 0.035 mm cutting head size. Representative suitablehomogenizers for this purpose include emulsifiers or micro-cutters,available from Stephan Machinery Corporation, located in Columbus, Ohioor high-shear mixers available from Silverson, located in EastLongmeadow, Mass. or the like.

In a step to control microorganisms, the temperature of the homogenateis kept cold throughout the process (33-40° F.). The cold temperature ismost effective for separating the fat from the protein. This unitoperation is accomplished while the pH is still near the pH of theinitial muscle. An alternative is to add enough food-grade acid to bringthe composite pH to the isoelectric point. Typically, the isoelectricpoint is about pH 5.5, but it can vary from species to species. At theisoelectric point, proteins are least able to form emulsions with lipidmolecules, and, therefore, more lipid renders away from the proteinsduring the extraction process. Once the tissue is homogenized, it isready to be adjusted to a low pH.

The resultant homogenate is directed to step 22 wherein it is mixed witha food grade acid 24 such as dilute hydrochloric acid, dilute phosphoricacid, dilute citric acid, ascorbic acid, tartaric acid or mixturesthereof or the like in order to reduce the pH of the homogenate tobetween pH 3.6 and pH 4.4, preferably between pH 3.6 and pH 3.8 todissolve animal muscle tissue thereby to obtain a satisfactory yield ofprotein such as 80% yield or higher in an acidic protein solutionthereof while retaining the fat portion in solid form. It is preferredto utilize hydrochloric acid since its use results in more significantreduction of viable microorganisms in the acidic protein solution.

Acidification of the proteins under low salt conditions has been shownto unfold the proteins, which is believed to create more surface areaalong the proteins and hence more potential water binding sites. Oncethe proteins are soluble, the fat renders away from the proteins andfloats to the surface of an aqueous acidic solution. Other potentialimpurities, including any residual bone, skin or sinew, stay insolubleas well. The pH is adjusted to 3.6 to 4.4 to obtain the desired color ofthe final product. As an example, the approximate amount of acid neededto effect solubilization of the muscle proteins is approximately 0.15 to0.80 weight %, e.g. 0.0.198 weight % based on the weight of HCl to totalweight (pH 3.74). This amount is dependent on the desired low pH (pH 3.6or 4.4) and also on the pH of the starting material. Suitable mixers toeffect this step include Lightnin Mixers available from SPX Corporation,located in Charlotte, N.C. or the like.

The resultant mixture of acidic solution of animal muscle protein andsolid fat then is directed to separation step 26 such as a decantercentrifuge and/or screen filter 26 to separate the acidic proteinsolution from the solid fat.

Subsequent to the solubilization of the proteins and removal ofimpurities and fat, the proteins are subjected to an increase in pH suchas by the addition of diluted, food-grade base such as sodium hydroxide(NaOH) or sodium bicarbonate (NaHCO₃). The base is added until theisoelectric point is obtained and the proteins refold and rejoin witheach other to form large, fiberized molecules. Upon reaching theisoelectric point pH, the proteins easily release their closely alignedwater molecules, and the moisture content can be returned to themoisture content found in meat or consistent with LFTM. The solid fat instep 28 is optionally mixed with a food grade alkali to separate waterfrom fat and to neutralize the fat. Optionally, cold potable water fromstep 29 can be added to the fat in step 28. The alkali promotesseparation of fat from water. The fat then is filtered in step 31 toremove water from fat and reduce the water content from about 70 to 50weight percent to about 30 to 20 weight percent. Optionally, the fat canbe refrigerated or frozen in step 33. Suitable filtration apparatusinclude vibrating screen available from Sweco Corporation, located inFlorence, Ky. or the like. The screens have a size between about 4000micron and about 2000 microns, preferably between about 3500 microns andabout 2500 microns. Additional base can be added in step 34 to bring thepH of the precipitated proteins back to the original pH of the tissue.This assures that the base (NaOH or NaHCO₃) has fully reacted with andconsumed all of the previously added acid such as HCL or citric. Anoptional step is to direct the protein product to a unit operation 35which removes water to concentrate the liquid for the purpose ofcreating larger fibers upon raising the pH. The unit operation couldconsist of any device found to remove water in a continuous or batchmanner, such as an evaporator or more desirable an ultrafiltration unit.The amount of water removed can vary, however, greater amounts of waterremoved results in larger and more robust and sturdy fibers andincreased protein recovery. The resultant protein product is a viscoussediment containing protein at a concentration of about 4-14 percent byweight or higher to produce a protein containing solution which isdirected to mixing step 34 wherein it is mixed with food grade alkaline36 such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, orthe like. The protein product is precipitated in step 38 and isrecovered such as by centrifugation and filtration in step 40.Optionally, an ultrafiltrate retentate having a >5000-10000 molecularweigh cut off (MWCO) is recovered in step 41. This ultrafiltrate has anelevated concentration of myoglobin having a red color and can beblended as desired with the precipitated protein in step 43. Thisresults in a protein product having an improved red color and reducedsodium content. The sodium is concentrated in the lower molecular weightfraction that is discarded. The resultant product has improved redcolor, desired reduced sodium and is obtained by a process (pH 3.6-4.4)that provides high yield of protein from the trimmings of about 80% orgreater. Thus, the process of this invention, provides a greatlyimproved protein product over the available prior art.

The protein product from step 40 contains 14 percent or greater byweight protein, contains less than 10 percent by weight fat, is producedat a temperature less than 110° F., can be frozen within 30 minutes instep 42 from process completion, does not allow a significant increasein bacteria and, in the embodiment wherein the protein precipitated withalkali does not retain chemicals or additives other than a lowconcentration of salt such as sodium chloride or the like.

The meat protein products of this invention are not significantlyaltered by the processing method of this invention. An examination ofthe proteins associated with the starting meat source and the lean coldprocessed meats (precipitated refolded protein) shows that theextraction process is mild enough not to effect changes in the proteinsthroughout the entire process. It also shows that very little to nohydrolysis has occurred during the processing, partly due to the lowtemperature. Refolding of the protein also does not affect its profile.

In summary, the process of this invention produces protein in higheryields as compared to the prior art, contains fewer microorganisms ascompared to the prior art and is in a form by which it can be moreeasily mixed with meat as compared to the products of the prior art. Inaddition, the fat product obtained is stabilized against oxidation.

The following examples illustrate this invention and are not intended tolimit the same.

Example I

A test was performed to examine the degree of hydrolysis comparing theamount of non-protein nitrogen compared to the amount of proteinnitrogen. Results are shown in Table 1 for Lean Cold Processed Pork &Beef made using hydrochloric acid and sodium hydroxide, and unprocessed,raw pork and beef muscle by the process of FIG. 1.

TABLE 1 Non Protein Nitrogen Protein Nitrogen Sample # (NPN) (%) (PN)Ratio NPN/PN Raw Beef 0.26 2.47 0.11 Lean Cold <0.02 1.48 <0.01Processed Beef Raw Pork 0.47 3.20 0.15 Lean Cold 0.05 1.62 0.03Processed Pork

When the ratio of NPN/PN was measured, an average of 0.03 for Lean ColdProcessed Pork and an average 0.15 for raw pork muscle were obtained.The averages for Lean Cold Processed Beef and beef muscle were <0.01 and0.11, respectively. The higher the percentage of NPN, the greater theamount of hydrolysis has taken place. US Food and Drug (FDA) has set astandard of >0.62 for “highly hydrolyzed” proteins. Values for the LeanCold Processed Meat proteins indicate very little hydrolysis hasoccurred, especially since the value is only approximately 20% for porkand <9% for beef of the value found for comparable whole raw meats,which appears to have not undergone much significant hydrolysis.

Finally, the amino acid content is similar between the starting beef andpork muscle and the lean cold processed meat from the same muscle. Asshown below in Tables 2 and 3, the amino acid percentages found for bothpork or beef show very little differences between the starting muscleand the lean cold processed meat. There were 45.44% essential aminoacids in pork muscle and 44.97% in the lean cold processed pork. Thebeef values were similar with 42.81% essential percentage for thestarting beef and 44.90% for the lean cold processed beef.

TABLE 2 Amino acid profile of pork muscle and lean cold processed pork(protein extracted from the same pork muscle using low pHsolubilization, processed according to U.S. Pat. No. 6,005,073). Low pHsolubilized protein Protein from Pork from same Pork Amino acid (% oftotal protein) (% of total protein) Aspartic acid 10.92 11.48 Threonine*4.53 4.59 Serine 5.17 5.22 Glutamic Acid 17.26 17.68 Glycine 4.85 4.17Alanine 5.97 5.84 Valine* 4.64 4.96 Methionine* 3.36 3.55 Isoleucine*4.42 4.43 Leucine* 8.79 8.87 Tyrosine 3.57 3.91 Phenylalanine* 4.90 5.16Lysine* 10.55 10.33 Histidine* 4.26 3.08 Argine 6.82 6.73 Essentialamino acids (%) 45.44 44.97

TABLE 3 Amino acid profile of beef muscle and lean cold processed beef(protein extracted from the same beef muscle using low pHsolubilization, processed according to U.S. Pat. No. 6,005,073 Low pHsolubilized protein Protein from Beef from same Beef (% of totalprotein) (% of total protein) Aspartic acid 10.65 10.99 Threonine* 4.394.54 Serine 5.59 5.57 Glutamic Acid 16.25 17.44 Glycine 7.72 4.54Alanine 6.72 5.97 Valine* 4.46 4.46 Methionine* 2.86 3.11 Isoleucine*3.79 4.14 Leucine* 8.39 9.00 Tyrosine 3.20 3.50 Phenylalanine* 4.73 4.78Lysine* 10.79 11.70 Histidine* 3.40 3.18 Argine 7.06 7.09 Essentialamino acids (%) 42.81 44.90 Essential amino acids are designated*

Thus, analytical data of the amino acids and proteins demonstrate thatthe lean cold processed meat retains the nutritional value, proteinprofile, and character of meat.

Example 2

From the perspective of microbial reduction, the process formanufacturing refolded protein of this invention has an advantage to theprocess for lean finely textured meat because in the process of thisinvention, is processed under cold conditions and the proteins will notsolubilize, hence the process will not work without a certain amount offood-grade acid, which inhibits microbes. In other words, in order toobtain specified yields for the product, certain benchmarks in pH, andthese pH levels are what inhibits microbes are reached. Thus, there areinherent controls in the processing of the products of this inventionthat enhance product safety. Analytic tests demonstrate the processeffectively produces a 1-3 log reduction of the microbes as compared tothe starting meat.

TABLE 4 Microbiological Results for Pork Starting Precipitated StartingPrecipitated Starting Precipitated Analyte Pork #1 Pork #1 Pork #2 Pork#2 Pork #3 Pork #3 Aerobic Plate Count >250000/g     2900/g  200000/g   4200/g  120000/g    2800/g  Coliform(MPN) <3/g <3/g  <3/g  <3/g  <3/g <3/g E. Coli 0157:H7 Neg./25 g Neg./25 g Neg./25 g Neg./25 g Neg./25 gNeg./25 g Listeria mono. Neg./25 g Neg./25 g Neg./25 g Neg./25 g Neg./25g Neg./25 g Staphylococci <10/g  <10/g  <10/g <10/g <10/g <10/g Yeast40/g 20/g 110/g <10/g 690/g <10/g Mold 30/g 10/g <10/g <10/g <10/g <10/gStarting Precipitating Starting Precipitating Starting PrecipitatingAnalyte Pork #4 Pork #4 Pork #5 Pork #5 Pork #6 Pork #6 Aerobic PlateCount 64000/g  50/g >250000/g   240/g >250000/g   250/g Coliform(MPN)   <3/g  <3/g  15/g  3.6/g  7.2/g  3.6/g E. Coli 0157:H7 Neg./25 gNeg./25 g Neg./25 g Neg./25 g Neg./25 g Neg./25 g Listeria mono. Neg./25g Neg./25 g Neg./25 g Neg./25 g  Pos./25 g Neg./25 g Staphylococci  25/g <10/g <10/g <10/g <10/g <10/g Yeast  570/g <10/g  90/g <10/g290/g <10/g Mold  <10/g <10/g <10/g <10/g <10/g <10/g

TABLE 5 Microbiological Results for Beef Starting Precipitated StartingPrecipitated Starting Precipitated Analyte Beef #1 Beef #1 Beef #2 Beef#2 Beef #3 Beef #3 Aerobic Plate Count 48000/g  8100/g  >250000/g  4300/g  >250000/g   6900/g  Coliform(MPN)  15/g  <3/g NA NA NA NA E.Coli 0157:H7 Neg./25 g Neg./25 g Neg./25 g Neg./25 g Neg./25 g Neg./25 gListeria mono. Neg./25 g Neg./25 g Neg./25 g Neg./25 g Neg./25 g Neg./25g Staphylococci <10/g <10/g <10/g  18/g <10/g <10/g Yeast <10/g <10/g 50/g <10/g  10/g <10/g Mold  10/g  30/g <10/g <10/g <10/g <10/gStarting Precipitating Starting Precipitating Starting PrecipitatingAnalyte Beef #4 Beef #4 Beef #5 Beef #5 Beef #6 Beef #6 Aerobic PlateCount 46000/g  3800/g  37000/g  430/g 33000/g  2800/g  Coliform(MPN) 3.6/g  <3/g  <3/g  <3/g  <3/g  <3/g E. Coli 0157:H7 Neg./25 g Neg./25 gNeg./25 g Neg./25 g Neg./25 g Neg./25 g Listeria mono. Neg./25 g Neg./25g Neg./25 g Neg./25 g Neg./25 g Neg./25 g Staphylococci <10/g <10/g<10/g <10/g <10/g <10/g Yeast  80/g 240/g  20/g <10/g  90/g <10/g Mold<10/g <10/g <10/g <10/g <10/g  10/g

Example 3

This example illustrates that recovery of protein from meat trimmingsmust be effected at a pH of 3.6 or above in order to recover a proteinproduct from satisfactory color. This example also illustrates thatinitially obtaining protein having an unsatisfactory color cannot bereversibly converted to a protein product having a satisfactory color.

The results obtained in Table 6 were obtained with 40 g samples ofground beef. To each sample was added 160 ml of cold tap water (40° F.).The samples were then homogenized to a particle size of about 100microns. The pH of each sample was adjusted with 1M food gradehydrochloric acid to a pH set forth in Table 6. Each sample wascentrifuged for 8 minutes at 5000 g at 4° C. and then filtered throughglass wool to separate solid fat from protein liquid composition. 40 mlof each liquid portion was poured into a container on top of whitepaper. Each sample was then measured twice with each sample with aMinolta colorimeter that measures L*, a* and b* values as set forthabove.

The average L*, a* and b* were then computed as shown in Table 6.

TABLE 6 Color Measurements - Ground Beef pH L* (1) a* (1) B* (1) L* (2)a* (2) b* (2) L* (AVG) a* (AVG) b* (AVG) 5.8a 75.33 14.63 15.53 61.9530.29 21.55 68.64 22.46 18.54 5.8b 71.40 18.35 16.59 76.92 13.93 15.3174.16 16.14 15.95 5.8 (AVG) 71.40 19.30 17.25 3.8a 56.92 25.11 21.0158.77 23.53 20.80 57.85 24.32 20.91 3.8b 55.57 26.40 21.19 59.18 23.5820.89 57.38 24.99 21.04 3.8 (AVG) 57.61 24.66 20.97 3.6 a 56.01 20.3820.46 57.35 19.46 20.54 56.68 19.92 20.50 3.6b 57.72 21.47 20.92 58.6320.90 20.81 58.18 21.19 20.87 3.6 (AVG) 57.43 20.55 20.68 3.5a 58.8015.03 20.67 61.09 13.97 20.40 59.95 14.50 20.54 3.5b 59.69 13.76 20.6461.92 12.84 20.32 60.81 13.30 20.48 3.5 (AVG) 60.38 13.90 20.51 3.4 a57.06 14.59 20.62 61.79 12.73 20.14 59.43 13.66 20.38 3.4 b 57.96 14.4920.82 60.16 13.60 20.54 59.06 14.05 20.68 3.4 (AVG) 59.24 13.85 20.533.3a 61.58 12.33 20.52 65.48 10.78 19.50 63.53 11.56 20.01 3.3b 58.7813.62 20.84 61.65 12.45 20.38 60.22 13.04 20.61 3.3 (AVG) 61.87 12.3020.31 3.3 to 3.8 a 57.77 19.36 20.46 59.37 18.39 20.45 58.57 18.88 20.463.3 to 3.8 b 57.61 16.67 20.56 57.47 16.70 20.56 57.54 16.69 20.56 3.3to 3.8 (AVG) 58.06 17.78 20.51

Example 4 Reduced Sodium

The sodium contents of regular store bought beef (85% lean ground) andpork (chops) determined and compared those to Lean Finely Textured Beefproduced commercially using the process of U.S. Pat. No. 5,871,795 andLean Cold Processed Beef and Pork. Sodium content was analyzed using anICP sample preparation and the emission spectrometry method described inAOAC 984.27. Although the HCl and NaOH combine to create water and salt,the salt content of the treated meat is comparable to the untreatedmeat. It was found through experimentation that the average sodiumcontent of untreated beef is 68.38 mg/100 g and untreated pork is 74.18mg/100 g. A sample of Lean Finely Textured Beef was found to have 122mg/100 g. The sodium content in the Lean Cold Processed Beef was 46.mg/100 g and Lean Cold Processed Pork was 71.80 mg/100 g

As shown in Table 6, the protein samples processed at pH 3.6, 3.8 and5.8 have a red color while the protein samples processed at pH 3.3, 3.4and 3.5 have a brown color. In addition, the protein sample processed atpH 3.3 and then having its pH increased to pH 3.8 retained its browncolor initially produced at 3.3. Thus, the production of brown colorproduct can not be converted to a red color product.

Example 5 Fat Oxidation

To examine the extent of oxidation that had occurred to the phase, thethio-barbituric acid reactive substance (TBARS) procedure described byLemon (1975) (Lemon, D. W. 1975 An Improved TBA test for rancidity, NewsSeries Circular No. 51, Halifax Laboratory, Scotia, Canada). For thecontrol fat from fresh ground beef (80:20) was extracted, mixed withwater and placed into a sealed poly bag which was further placed into awater bath at 107° F. After 30 minutes, the mixture was centrifuged for20 minutes at 3,000×g in a Sorval centrifuge. The lipid phase wasdrained off and the lipid was placed into Whirl-pak bags and stored atrefrigerated temperatures (34-40° F.) for seven days prior to TBARSanalysis. This control is how the industry currently produces LeanFinely Textured Beef and the fat phase from this process. Beef fat fromthe Lean Cold Processed Meat process is extracted using the proceduredescribed above and 1) was placed into Whirl-pak bags and stored atrefrigerated temperatures (34-30° F.) for seven days prior to TBARSanalysis or was 2) mixed with cold water 50:50 (w/w) and then stored atrefrigerated temperatures (34-40° F.) for seven days prior to TBARSanalysis.

Controls had a value of 14.25±3.5 nmol/kg of TBARS whereas the (dry) fatsamples were found at 64±2.1 nmol/kg and the fat in water samples werefound to be 2.7±2.0 nmol/kg. In subsequent experiments the moisturecontent of the (dry) fat is 26.92% moisture with a peroxide value of0.25 meq/kg, and the fat with water sample to be 57.31% moisture with aperoxide number of <0.02 meq/kg. Peroxides were measured using thePeroxy Safe method (AOAC 03050). Controls had extensive oxidation whencompared to Lean Cold Processed Fat samples. It is peculiar that the fatsamples stored with water had lower oxidation values than the fat storeddry. Typically higher moisture contents in fats leads to higher rates ofoxidation. It may be that there was so much water that it diluted outthe pre-oxidants and made the oxidation reactions less active.

Example 6

Lean Cold Processed Beef was made for comparison purposes using 1.hydrochloric acid and sodium hydroxide and 2. citric acid and sodiumbicarbonate. Ground beef trim was mixed with cold water at a 1:4 ratioof beef to water. The mixture was homogenized using a Kitchen Aidhand-held mixer for 1 minute on high speed. One aliquot was reduced topH 3.6 using 2N HCl and another aliquot had its pH adjusted to pH 3.6using 2N citric acid. The resultant products were filtered through ametal screen with 1/16 inch perforations. Both filtrates were adjustedto pH 5.5 using 4M sodium hydroxide (HCl sample) or 6% (w/w) sodiumbicarbonate (citric acid sample). Product was filtered again to removewater. The final pH of the final product was adjusted to pH 6.5 usingadditional sodium hydroxide or sodium bicarbonate. Product was frozenand sent to Silliker Laboratories for proximate and sodium analyses.

TABLE 7 Analytical Data for Lean Cold Processed Beef made usingDifferent Acids and Bases Analyte Result Method HCL/NaOH Ash 0.23 AOAC920.153 Carbohydrate 0.74 Calculation Fat 4.68 AOAC 960.39 Moisture79.60 AOAC 991.46Bb Protein 14.75 AOAC991.20.1 Salt 0.17 AOAC 983.14Citric/Sodium bicarbonate Ash 0.31 AOAC 920.153 Carbohydrate .033Calculation Fat 4.49 AOAC 960.39 Moisture 80.15 AOAC 991.46Bb Protein14.72 AOAC991.20.1 Salt 0.05 AOAC 983.14

Results demonstrates that both acid/base combinations produce finalproducts that meet USDA chemical specifications for Lean Finely TexturedBeef (LFTB) of >14% protein and <10% fat. Both samples were alsoreddish/pink in color which is also a USDA requirement for LFTB and bothhad a mild beef taste with no off-tastes or odors.

Example 7 Sturdiness

Fresh beef (85% lean) was placed into a mixing container and cold waterwas added at a 1:4 ratio (beef:water). The mixture was homogenized usinga Kitchen Aid hand mixer on high speed for 2 min. The homogenate wasthen adjusted to pH 3.6 using hydrochloric acid (2M). Product wascentrifuged in a Sorvall Model RC-5B centrifuge for 20 minutes at 8,000RPM. The acidified solution was accurately adjusted, by the addition ofcold water, to 2.5% Brix using a hand-held refractometer. A sample ofthe starting material was taken. Two gallons of the remaining solutionwas placed into a ultrafiltration test unit (Koch Membrane, Wilmington,Mass.) equipped with a 720034 column for water removal. Product was runfor 1.05 hrs until the refractometer displayed a reading of 5% Brix.Individually the products were adjusted to pH 5.5 using sodium hydroxide(4M) and the precipitates were collected for analysis.

The precipitated products made from the 2.5% Brix and 5.0% Brixsolutions were measured for fiber length development and sturdiness ofthe fibers. Sturdiness was determined by placing equal 200 g beefweights (minus the water weights) on a 1000 micron screen and swirlingunder constant motion for 2 minutes before weighing the resultantretentate.

The fiber length of precipitated product made from the starting solutionof 2.5% Brix ranged between 0.5 to 1.0 mm, compared to the fiber lengthmade from 5% Brix material which ranged from 1.5% Brix to 5 mm inlength. The smaller size of the 2.5% Brix particles requiredcentrifugation to effectively collect the precipitate, whereas thelarger fibers were collected in a 1/16 inch wire screen.

To determine sturdiness the average weights of the precipitated productsafter the swirling filtering step were taken. The results were 127 gfrom the 5% Brix solution and 82 g from the 2.5% Brix solutions. Thisrepresents a 54.9% increase in yield if one captures the precipitatedproduct from a 5% Brix solution versus obtaining the same product from a2.5% solution. We refer this as sturdiness because what appears tohappen with the product from the 2.5% solution, is that the swirlingmotion causes a shearing of the product which reduces its particle sizeand allows more to pass through the 1000 micron screen. The swirlingshear action appears to not be able to reduce the particle size of the5% Brix product.

The invention claimed is:
 1. A process for recovering a proteincomposition having a color of 75 to 52 L*, 25 to 15 a*, and 23 to 16 b*obtained from meat trimmings containing fat and protein, wherein themeat trimmings are obtained from beef and wherein the meat trimmingshave an average fat content between about 50% and 80% by weight and alean content between about 20% and 50% by weight, said processcomprising the steps of: a) comminuting the meat trimmings in water, b)adding a food grade acid to the comminuted meat trimmings to obtain a pHin the range of 3.6 to 4.4 thereby to solubilize the protein, c) afteraddition of the food grade acid in step b), separating solid fat fromsolubilized protein, and d) adding a food grade alkali to thesolubilized protein to increase the pH in the solubilized protein and toprecipitate the solubilized protein to produce a protein compositionwith a color of 75 to 52 L*, 25 to 15 a*, and 23 to 16 b*, wherein theprotein composition has 14% or greater by weight protein and less than30% by weight fat.
 2. The process of claim 1, wherein said pH in step bis in the range of 3.6 to 3.8.
 3. The process of claim 1, wherein a foodgrade acid is added in step a.
 4. The process of claim 2, wherein a foodgrade acid is added in step a.
 5. The process of claim 1, wherein saidfood grade acid is taken from the group consisting of citric acid andhydrochloric acid.
 6. The process of claim 2, wherein said food gradeacid is taken from the group consisting of citric acid and hydrochloricacid.
 7. The process of claim 1, wherein said food grade acid is citricacid and said food grade alkali is sodium bicarbonate.
 8. The process ofclaim 3, wherein said food grade acid is citric acid and said food gradealkali is sodium bicarbonate.
 9. The process of claim 1, wherein theprocess additionally comprises filtering the precipitated proteincomposition thereby to produce a filtrate thereof and a proteincomposition as a retentate thereof, ultra-filtrating the filtrate toobtain a myoglobin rich solution, and mixing the protein composition andthe myoglobin rich solution.
 10. The process of claim 3, wherein theprocess additionally comprises filtering the precipitated proteincomposition thereby to produce a filtrate thereof and a proteincomposition as a retentate thereof, ultra-filtrating the filtrate toobtain a myoglobin rich solution, and mixing the protein composition andthe myoglobin rich solution.
 11. The process of claim 1, wherein wateris removed from said protein in step c) prior to adding said food-gradealkali.
 12. The process of claim 9, wherein said food-grade acid is afood-grade citric acid and food-grade alkali is a food grade sodiumbicarbonate.
 13. The process of claim 10, wherein said food grade acidis taken from the group consisting of citric acid and hydrochloric acid.14. The process of claim 1, wherein the protein composition has lessthan 10% by weight fat.
 15. A process for recovering a proteincomposition having a color of 75 to 52 L*, 25 to 15 a*, and 23 to 16 b*,said protein composition is recovered from meat trimmings, wherein themeat trimmings are beef trimmings and wherein the meat trimmings have anaverage fat content of at least about 50% by weight, said processcomprising the steps of: a) comminuting the meat trimmings in water, b)adding a food grade acid to the comminuted meat trimmings to obtain a pHin the range of 3.6 to 4.4 thereby to solubilize the protein, c) afteraddition of the food grade acid in step b), separating solid fat fromthe solubilized protein; and d) adding a food grade alkali to thesolubilized protein to precipitate the solubilized protein to producethe protein composition having a color of 75 to 52 L*, 25 to 15 a*, and23 to 16 b*, wherein the protein composition has 14% or greater byweight protein.
 16. The process of claim 15, wherein said pH in step bis in the range of 3.6 to 3.8.
 17. The process of claim 15, wherein afood grade acid is added in step a.
 18. The process of claim 15, whereinsaid food grade acid is taken from the group consisting of citric acidand hydrochloric acid.
 19. The process of claim 15, wherein said foodgrade acid is citric acid and said food grade alkali is sodiumbicarbonate.
 20. The process of claim 15, wherein the processadditionally comprises filtering the precipitated protein compositionthereby to produce a filtrate thereof and a protein composition as aretentate thereof, ultra-filtrating the filtrate to obtain a myoglobinrich solution, and mixing the protein composition and the myoglobin richsolution.
 21. The process of claim 15, wherein water is removed fromsaid protein in step c) prior to adding said food-grade alkali.
 22. Theprocess of claim 15, wherein the protein composition has less than 10%by weight fat.
 23. A protein composition having a color of 75 to 52 L*,25 to 15 a*, and 23 to 16 b* obtained from meat trimmings containing fatand protein, wherein the meat trimmings are beef trimmings and whereinthe meat trimmings have an average fat content of at least about 50% byweight, said protein composition recovered from a process comprising thesteps of: a) comminuting the meat trimmings in water, b) adding a foodgrade acid to the comminuted meat trimmings to obtain a pH in the rangeof 3.6 to 4.4 thereby to solubilize the protein, c) after addition ofthe food grade acid in step b), separating solid fat from thesolubilized protein; and d) adding a food grade alkali to thesolubilized protein to precipitate the solubilized protein to producethe protein composition having a color of 75 to 52 L*, 25 to 15 a*, and23 to 16 b*, wherein the protein composition has 14% or greater byweight protein.
 24. The process of claim 23, wherein said pH in step bis in the range of 3.6 to 3.8.
 25. The process of claim 23, wherein afood grade acid is added in step a.
 26. The process of claim 23, whereinsaid food grade acid is taken from the group consisting of citric acidand hydrochloric acid.
 27. The process of claim 23, wherein said foodgrade acid is citric acid and said food grade alkali is sodiumbicarbonate.
 28. The process of claim 23, wherein the processadditionally comprises filtering the precipitated protein compositionthereby to produce a filtrate thereof and a protein composition as aretentate thereof, ultra-filtrating the filtrate to obtain a myoglobinrich solution, and mixing the protein composition and the myoglobin richsolution.
 29. The process of claim 23, wherein water is removed fromsaid protein in step c) prior to adding said food-grade alkali.
 30. Theprocess of claim 23, wherein the protein composition has less than 10%by weight fat.